I would highly recommend putting an overclock on your CPU. Running it at 4.2 is like putting around in a ferrari. In games like DCS, single core speed is king, so let that bad boy loose and see the improvement.
I'm running a i5-6600k at 4.3, which is an extremely tame OC, mainly because its air cooled and in a mini-ITX case. You will be impressed at the noticeable improvement with a stable OC.
Your system is badass, and I hope you enjoy it.